big refactoring

configurations/default.nix

@@ -1,18 +1,73 @@
 { inputs, ... }@flakeContext:
 let
+  lib = inputs.nixpkgs.lib;
   mkSystem = import ../lib/mkSystem.nix flakeContext;
+  xlibLib = import ../lib/xlib.nix { inherit lib; };
+
+  # One record per host. The attribute name IS the hostname, so it is written
+  # exactly once; `hostname` is only needed where the attribute name is not
+  # the real hostname (the `default` entry).
+  #
+  #   device   device type, must be a key of `devices` in lib/xlib.nix
+  #   modules  module body for this host
+  hosts = {
+    default = {
+      hostname = "nixos";
+      device = "minimal";
+      modules = [ ./any.nix ];
+    };
+    atoridu = {
+      device = "primary";
+      modules = [ ./mini-pc.nix ];
+    };
+    rydiwo = {
+      device = "secondary";
+      modules = [ ./mini-laptop.nix ];
+    };
+    otreca = {
+      device = "vds";
+      modules = [ ./vds.nix ];
+    };
+    sapphira = {
+      device = "server";
+      modules = [ ./server.nix ];
+    };
+    wsl = {
+      device = "wsl";
+      modules = [ ./wsl.nix ];
+    };
+  };
+
+  mkHost =
+    name:
+    {
+      device,
+      modules,
+      hostname ? name,
+      ...
+    }:
+    let
+      xlib = xlibLib.mkXlib {
+        inherit hostname;
+        type = device;
+      };
+    in
+    {
+      inherit xlib;
+      system = mkSystem { inherit xlib modules; };
+    };
 in
 {
-  nixosConfigurations = {
-    default = mkSystem (import ./any.nix); # default
-    atoridu = mkSystem (import ./mini-pc.nix); # atoridu
-    rydiwo = mkSystem (import ./mini-laptop.nix); # rydiwo
-    otreca = mkSystem (import ./vds.nix); # vds
-    sapphira = mkSystem (import ./server.nix); # sapphira
-    wsl = mkSystem (import ./wsl.nix); # wsl
-  };
+  nixosConfigurations = lib.mapAttrs' (
+    name: spec: lib.nameValuePair name (mkHost name spec).system
+  ) hosts;
+
+  # Per-host xlib values, for code that lives outside the module system
+  # (deploy, overlays, pkgs).
+  xlib = lib.mapAttrs' (name: spec: lib.nameValuePair name (mkHost name spec).xlib) hosts;
+
   nixOnDroidConfigurations = {
-    epral = import ./mobile.nix flakeContext; # epral (Android via nix-on-droid)
+    epral = import ./mobile.nix flakeContext; # epral (Android device via nix-on-droid)
     # Alias so a plain `nix-on-droid switch` from a local clone
     # (~/.config/nix-on-droid) picks up the device config without `#epral`.
     default = import ./mobile.nix flakeContext;